Addition agents for mineral oil lubricants and compositions containing the same



Patented Feb. 14, 1950 ADDITION AGENTS FOR MINERAL OIL LUBRICANTS ANDCOMPOSITIONS CONTAINING THE SAME Herschel G. Smith, Wallingiord, andTroy L. Cantrell, Lansdowne, Pa., and John G. Peters, Audubon, N. 3.,assignors to Gulf Oil Corporation, Pittsburgh, Pa", a corporation ofPennsylvania 4 No Drawing. Application June 12, 1947,

Serial No. 754,268

This invention relates to addition agents for mineral oil lubricants andcompositions containing the same, and more particularly, it is concernedwith addition agents for mineral oil lubricants which provide detergenteffects and inhibit the oxidative deterioration of said lubricants.

In the lubrication of internal combustion engines of all types,particularly when severe operating conditions are encountered, plainmineral lubricating oils often prove unsatisfactory in service becauseof the oxidative deterioration of the oil with the attendant depositionon the engine surfaces of varnish, gum and sludge. In turbine oils, theproblem of oxidation is further aggravated because in normal use turbineoils rapidly become contaminated with water.

The formation of varnishes, gums and sludges on engine surfaces is due,at least in part, to oxidation effects on the mineral lubricating oils.The presence of these substances is disadvantageous because theoxidation products of the oil tend to increase ring sticking and theproduction of further deposits on piston surf-aces and in fixed parts ofthe combustion chamber. sludges are formed in the crank case of theengine and the rate of corrosion of bearing surfaces is increased,especially with bearing alloys of the types now in use.

It is an object of this invention, therefore, to provide an additionagent for mineral oil lubricants which will prevent the formation of theenglne deposits encountered in the use of mineral oil lubricants. It isa further object of this invention to provide an addition agent formineral oil lubricants which will inhibit the oxidative deterioration ofsuch lubricants. It is a still further object of this invention toprovide an addition agent for mineral oil lubricants which serves thefunctions of (1) inhibiting the oxidative deterioration of the lubricantand (2) acting as a detergent to prevent ring sticking, varnishing orcoating of the metallic surfaces of internal combustion engines, as wellas a suspending or dispersing agent for dispersing very small particlesof deterioration products or contaminating materials in the oil.

These and other objects are achieved by the present invention whereinthere is provided as an addition agent for mineral oil lubricants asubstantiall neutral polyvalent metal salt of a compound having theformula:

wherein R is an alkyl radical having from 4 to 12 carbon atoms. We havefound that the above described polyvalent metal salts have excellentsolubility in mineral oils and will effectively act as detergents. Mostof th salts will also act to inhibit the oxidative deterioration of saidlubricants.

The substantially neutral polyvalent metal salts of our invention areprepared by the condensation of N-dimethylaniline, a phenol having apara-alkyl substituent of from 4 to 12 carbon atoms and formaldehyde.More specifically 2 mols of the alkylated phenol, 2 mols ofN-dimethylaniline and 3 mols of formaldehyde are condensed in thepresence of an activated clay catalyst, such as bentonite, fullersearth, fioridin and the like which has been acid treated in order toactivate the clay. The condensation is performed by heating thereactantsto a, maximum temperature of 350 F., preferably at a temperature rangingfrom to 300 F. The condensation may be considered complete when all ofthe formaldehyde is consumed, and results in the splitting 01? of 3 molsof water. The activated clay catalyst is preferabl used in an amount of5 to 10 per cent b weight of the total reactants, and serves thefunction of promoting the formation of light-colored. oil-solublecondensation products which are non-resinous in nature, instead ofresinous, highly-condensed insoluble materials. In lieu of formaldehyde,any formaldehyde-yielding compound, such as para-formaldehyde,trioxymethylene and the like, may be employed. In such case, the amountof formaldehyde-yielding compound used is based on the equivalent numberof mols of formaldehyde yielded. Accordingly, as used herein, the termto result in a substantially neutral salt. Alterna-.

tively, the salts may be prepared in one step by mixing the polyvalentmetal hydroxide or oxide, N-dimethylaniline, the phenol and formaldehydetogether and reacting the mixture. In lieu of forming the metal salts byreaction with the polyvalent metal oxide or hydroxide, alkali metalsalts may first be formed by neutralization of the condensation productwith an alkali metal hydroxide followed by a double decompositionreaction of the alkali metal salt with a water-soluble salt of a desiredpolyvalent metal.

The para alkyl phenol used in preparing our new addition agents has from4 to 12 carbon atoms in the alkyl group, and may thusinclude para alkylphenols such as butyl, amyl, hexyl, heptyl, octyl, decyl and dodecylphenols. The alkyl group may have a normal or branched chain structure.Such alkyl phenols are conveniently prepared by alkylating, in thepresence of a condensing agent such as concentrated sulfuric acid,phenol with an olefin, such as butene-l, isobutylene, the variousamylenes, di-isobutylene and triisobutylene. A preferred phenol ispara-tetramethylbutyl phenol obtained by alkylating phenol withdi-isobutylene in the presence of concentrated sulfuric acid.

As has been stated, the addition agents of our invention are polyvalentmetal salts. Polyvalent metals which may be used include divalent metalssuch as beryllium, barium, calcium, strontium, magnesium, zinc, cadmium,copper, lead, nickel, cobalt, etc. Trivalent metals such as aluminum,bismuth and chromium, as well as metals of higher valency, such as tin,may also be employed. A preferred subgroup of polyvalent metalscomprises the alkaline earth metals. Whereas all polyvalent metals formexcellent oil-soluble detergent salts in accordance with our invention,not all of them will yield salts which inhibit the oxidativedeterioration of mineral oil lubricants. Thus the copper and lead saltswill not ordinarily inhibit oxidative deterioration. However, where inaddition to detergency, antioxidant properties must be conferred on amineral oil lubricant, either the antioxidant salts of our invention orother known antioxidant compounds may be added in an amount suillcientto confer the desired effect.

The following example illustrates the preparation of our new additionagents:

Example I.Para-tetramethylbutyl phenol was conveniently prepared byintroducing 24.8 parts by weight of phenol and 31.4 parts by weight ofcommercial di-isobutylene polymer into a reaction vessel. The mixturewas then agitated and 1.2 parts by weight of 94-98% sulfuric acid wereadded over a period of 30 minutes. After the addition of the sulfuricacid, the temperature was maintained at 220 F. for a period of 24 hours.The reaction mixture was then cooled to 180 F. and was washed threetimes with parts by weight of water. The reaction temperature was notpermitted to exceed 220 F. Four hundred twelve pounds of the resultingpara-tetramethylbutyl phenol were placed in a reaction vessel along with242 pounds of N-dimethylaniline, 245 pounds of 37% aqueous formaldehyde,74 pounds of hydrated lime and 10 per cent by weight of the totalreactants of an acid activated bentonite clay. The vessel was thenclosed, attached to a reflux condenser and refluxed 6 hours at 210 F.The water was then stripped off, the temperature raised to 295 F. andthe product filtered. The product had the following properties:

Gravity, API 6.7 Color, NPA 5.5 Neutralization No 1.68

Ash: per cent. 7.!

The product obtained was the substantially neutral calcium salt of bis(2-hydroxy, 3-paradimethylaminobenzyl, 5 tetramethylbutyl, phenyl)methane having the formula:

0 (CHMNOCHQOILQCHONWHQ,

wherein R is the tetramethylbutyl radical. This product was a highlyviscous liquid.

The barium and aluminum salts of bis (2-hydroxy,3-paradimethylaminobenzyl, 5-tetram'ethylbutyl, phenyl) methane wereprepared by a procedure identical with that shown in Example I, exceptthat an amount of mineral lubricating oil equal to the weight of thereactants was added. The resulting solutions of the barium and aluminumsalts had the following properties:

Barium salt Aluminum in oil solusalt in oil tion solution 1 Slightlyalkaline.

The metal salts disclosed hereinabove are excellent addition agents formineral oil lubricant compositions. They are readily soluble in alltypes of mineral oils, that is, paraflinic, naphthenic, or mixed basemineral oils and can be blended with them in high proportions. Thisexcellent solubility of our new addition agents enables the preparationof concentrated solutions thereof which may then be diluted down to theproportions desired in the final mineral oil lubricant composition. Asstated, our new addition agents confer excellent detergent properties onthe mineral lubricating oils with which they are incorporated, and inmost instances also inhibit oxidative deterioration of the minerallubricating oil. For these purposes our new addition agents aregenerally added in minor amounts, say from 0.1 to 10.0 per cent byweighton the mineral oil. Ordinarily, 0.1 per cent by weight issuflicient to effect the desired improvement.

The following examples illustrate the remarkable improvements effectedby the use of our new addition agents.

Example II.-An improved motor oil was prepared by treating a motor oilwhich had been highly refined with aluminum chloride with 0.5% by weightof the addition agent prepared in sccordanee with Example I. Acomparison oi the improved oil and base oil follows:

Example [IL-An improved steam turbine oil was prepared by treating abase turbine oil stock with 0.5% by weight of the agent preparedaccording to Example I. A comparison of the improved oil and base oilfollows:

Base Oil gg Gravity, API 2d 8 26. 6 Oxidation Test:

ABTM-Proposed- 203 F., 3 L. Oxygen/Hr;

Time Oxidized, Hr 180 2000+ Neutralization No 2.

The above examples show the remarkable oxidation stability imparted tomineral oil lubricants by the use of our new addition agents, as well asthe efiective detergent effects obtained. The oxidation test referred tois a standard test described in ASTM Standards on Petroleum Products andLubricants, September 1943, pages 17-20. Briefly, the test comprisessubjecting the oil sample to oxygen at a temperature of 95 C. (203 F.)in the presence of water and an ironcopper catalyst, and determining thetime required to build up a neutralization number of 2. As may be seenfrom the above examples, an oxidation stability of more than 2000 hourshad already been attained but the neutralization number had not yetreached 2. The motor 011 service test referred to in Example 11 is fullydescribed in U. S. Patent 2,378,442.

While we have shown in the examples the preparation of compoundedlubricating oils, our invention is not limited thereto but comprises allmineral oil lubricant compositions containing our new addition agents,such as greases and the like.

We claim:

1. A substantially neutral polyvalent metal salt of a compound havingthe formula:

in on (omhN-O-cn sin-O0 HON(CH:)1

I R R wherein R is an alkyl radical having from 4 to 12 carbon atoms.

2. The salt of claim 1, wherein the metal salt is a divalent metal salt.

3. The salt of claim 1, wherein the metal salt is a trivalent metalsalt.

4. The salt of claim 1, wherein the metal salt is an alkaline earthmetal salt.

5. The salt of claim 1, wherein the metal salt is a calcium salt.

6. The salt of claim 1, wherein the metal salt is a barium salt.

7. The salt of claim 1, wherein the metal salt is an aluminum salt.

0.,The salt 0! claim 1, wherein R. is the tetramethylbutyl radical.

9. The substantially neutral calcium salt of his (Z-hydroxy,S-paradimethylaminobenzyl, 5- tetramethylbutyl, phenyi) methane, havingthe formula c Ham-Q0 n'Qcn'Qom-Qmcmb wherein R is the tetramethylbutylradical.

10. A lubricant composition comprising a major amount of a minerallubricating oil and a minor amount, suillcient to confer detergentproperties on the composition, of a substantially neutral polyvalentmetal salt of a compound having the formula:

wherein R is an allwl radical having from a to 12 carbon atoms.

11. The composition of claim 10, wherein t metal salt is a divalentmetal salt.

12. The composition of claim 10, wherein the metal salt is a trivalentmetal salt.

13. The composition of claim 10, wherein the metal salt is an alkalineearth metal salt.

14. The composition of claim 10, wherein the metal salt is present in anamount of from 0.1 to 10.0 per cent by weight on the mineral oil.

15. A lubricant composition comprising a major amount of a minerallubricating oil and a minor amount, from 0.1 to 10.0 per cent by weighton the mineral lubricating oil, ofasubstantially neutral polyvalentmetal salt of a compound having the formula:

OH OH (Cmim-O-CHQcnficm-Omcm). R

c/ o HmNO-CH 5 cm-OcmO-Nwmn Tl wherein R is the tetramethylbutylradical.

20. The process which comprises forming a substantially neutralpolyvalent metal salt of a compound obtained by condensing 2 mols of 7 aphenol having a para-alkyl substltuent o! from 4 to 12 carbon atoms, 2mols oi N-dimethylaniline and 3 mols of formaldehyde in the presence 0!an activated clay catalyst.

21. The process which comprises forming in a mineral lubricating oil asubstantially neutral polyvalent metal salt obtained by condensing at atemperature not in excess of 350 1". 2 mols ot a rphenol having apara-alkyl substituent of ;from 4 to 12 carbon atoms, 2 mols ofN-dimethylanlline and 3 mols of formaldehyde in the presence of anactivated clay catalyst, and recovering a solution in said minerallubricating oil of the substantially neutral polyvalent metal salt soobtained.

HERSC'HEL G. SMITH. TROY L. CANTRELL. JOHN G. PETERS.

The iollowing references are of record in the file of this patent:

UNITED STATES PA'I'EN'IB Number Name Date 2,190,732 Reddelien Rb. 20,1940 2,363,134 McCleary Nov. 21, 1944 2,414,729 Fleming Jan. 21, 124'!2,415,833 Mikeska Feb. 18, 1947 2,420,893 McNab May 20, 1947 2,431,011Zimmer Nov. 18, 194'! 2,434,396 Cook Jan. 13. 1948

10. A LUBRICANT COMPOSITION COMPRISING A MAJOR AMOUNT OF A MINERALLUBRICATING OIL AND A MINOR AMOUNT, SUFFICIENT TO CONFER DETERGENTPROPERTIES ON THE COMPOSITION, OF A SUBSTANTIALLY NEUTRAL POLYVALENTMETAL SALT OF A COMPOUND HAVING THE FORMULA: